scripted-diff: Rename interfaces::WalletClient to interfaces::WalletLoader

Name has been confusing since it was introduced, and it was pointed in
recent review club as https://bitcoincore.reviews/10102 that it was
particularly unclear how interfaces::WalletClient was different from
interfaces::Wallet.

-BEGIN VERIFY SCRIPT-
ren() { git grep -l "$1" src | xargs sed -i "s/$1/$2/g"; }
ren WalletClient WalletLoader
ren walletClient walletLoader
ren wallet_client wallet_loader
ren "wallet clients release the wallet" "wallet pointer owners release the wallet"
ren "wallet client" "wallet loader"
ren "Wallet client" "Wallet loader"
-END VERIFY SCRIPT-

src/node/context.h

@@ -23,7 +23,7 @@ namespace interfaces {
 class Chain;
 class ChainClient;
 class Init;
-class WalletClient;
+class WalletLoader;
 } // namespace interfaces
 
 //! NodeContext struct containing references to chain state and connection
@@ -52,7 +52,7 @@ struct NodeContext {
     std::vector<std::unique_ptr<interfaces::ChainClient>> chain_clients;
     //! Reference to chain client that should used to load or create wallets
     //! opened by the gui.
-    interfaces::WalletClient* wallet_client{nullptr};
+    interfaces::WalletLoader* wallet_loader{nullptr};
     std::unique_ptr<CScheduler> scheduler;
     std::function<void()> rpc_interruption_point = [] {};